BODY COMPOSITION

By David MaretHouse - Master fitness trainer, owner of MaretHouse Fitness, and co-owner of JD Max Fitness

Body composition is the percentage of your body fat mass (adipose tissue) in relation to your lean body mass (muscle, organs, and bones).  The ideal percentage of body fat varies with each individual taking into consideration variables such as body type, hereditary factors, age, sex, and activity levels.  Below is a chart that gives different health ranges of body composition depending on age and sex.

Women

   Age           Underfat    Healthy Range    Overweight     Obese
20-40 yrs     Under 21%       21-33%           34-39%     Over 39%
41-60 yrs     Under 23%       23-35%           36-40%     Over 40%
61-79 yrs     Under 24%       24-36%           37-42%     Over 42%

Men

   Age           Underfat   Healthy Range     Overweight     Obese
20-40 yrs      Under 8%        8-19%            20-25%     Over 25%
41-60 yrs     Under 11%      11-22%            23-27%     Over 27%
61-79 yrs     Under 13%      13-25%            26-30%     Over 30%

Body composition testing is the best way to monitor the effects of diet and exercise.  Ideal body weight and the BMI (body mass index) calculations are becoming more obsolete since neither of the two take into account genetic variables other than an individual’s weight and height.

There are many ways to analyze body composition currently.  Each method has its own advantages and disadvantages.  

Caliper body fat testing is probably the most traditional and well known method for testing body composition.  Skin fold calipers are small pinching devices that measures subcutaneous body fat (between skin and muscle) on your body.  It has a +/- 3-8% error ratio and is not ideal to use on those who are obese; however, it is a non-invasive method that does not require much time and is easy to use.  

Bio-impedance (BIA) fat testing is becoming more widely used due to its ease of use.  It is done by hooking up an electrode to your foot or hand and allowing an electrical low voltage impulse to shot up one leg or arm and down the other to estimate body fat percentage.  Bio-impedance testing has a +/- 5-8% error ratio and is extremely sensitive to hydration levels of the subject being tested.  

Duel energy X-ray absorptiometry body fat testing (DEXA) uses two x-ray energies to measure body fat percentage, muscle mass and bone mineral.  This testing, under the proper conditions, provide very accurate results while having a +/- 2% error ratio.  

Hydrostatic body fat testing (water dunk test) is the gold standard of body composition testing.  This test is preformed by an individual expelling all oxygen remaining in their lungs while submerged in a tank of water.  This is the most accurate technology available today with a +/- 1.5% error ratio.    

All of the above mentioned tests are useful methods; but they should be taken as indicators, and used to assess relative changes over several months.  Other ways to assess progress include how your cloths fit, overall energy levels, activity and sports performance and attainment of your specific goals.